Liquid ring machine and process for operating it

ABSTRACT

A liquid ring machine has one partial working chamber of the liquid ring machine which is separated from the supply of operating liquid and is drained of the operating liquid to the point where the part of the impeller rotating in this partial working chamber does not contact the operating liquid, and this partial chamber is blocked on the suction and/or discharge side. The liquid ring machine is able to be optionally partially switched off, thus allowing an adaptation to the specific process requirements.

BACKGROUND OF THE INVENTION

The invention relates to a method for operating a liquid ring machine,as well as to a liquid ring machine for implementing the method.

In the case of a liquid ring machine disclosed by German Patent C 961653, the working chamber is subdivided by a wall part that axiallysubdivides the impeller and by an intermediate wall of the housing shellarranged in the same plane with this wall part into two partial workingchambers of the same size. During operation, a liquid ring forms in eachpartial working chamber.

Separate suction and discharge connections are assigned to each partialworking chamber. In addition, the partial working chambers areinterconnected in the lower region by openings, making it possible forboth partial working chambers to be drained simultaneously through ashared outlet. A pump of this type is able to deliver two distinct gaseshaving different pressures at the same time.

The CH-A 285 570 discloses a two-stage liquid ring pump, whose firststage is designed for a larger output volume than its second downstreamstage. Such pumps generally experience difficulties when they have towork at a low vacuum.

In this case, the output volume of the first stage is substantiallygreater than that of the second stage. The second stage is not able toprocess the volume required by the first stage. As a result, blockingoccurs, which reduces pump efficiency and can also cause damage to thepump. This working point has to be run through at every start-upoperation of the pump. For this reason, it is provided in the case ofthis known pump for the second stage (high pressure stage) to be madeinactive by removing operating liquid for so long until the ratio of theintake volume to the final volume corresponds to the ratio of the outputvolume of the first stage to that of the second stage. So much operatingliquid is removed from the second stage, that its delivery isinterrupted. Thus, the liquid ring, which requires a correspondingamount of energy for its actuation, still remains in the second liquidstage.

This invention is directed to a method of adapting a liquid ring machineto various types of loading and to provide a liquid ring machine forimplementing this method.

SUMMARY OF THE INVENTION

The present invention solves this problem by a method for operating aliquid ring machine, whose apex lies in the geodetic upper area of theworking chamber and whose working chamber is divided up into at leasttwo partial working chambers, in the case of which method, at least onepartial working chamber of the liquid ring machine is separated from thesupply of operating liquid and is drained of the operating liquid atleast to the point where the part of the impeller rotating in thispartial working chamber does not come into contact with the operatingliquid. This partial working chamber is also blocked on the suctionand/or discharge side. The position of the apex in the geodetic upperarea of the working chamber is guaranteed in that the eccentricity ofthe impeller is selected so as to provide adequate clearance between theunattached blade ends of the impeller and the inner housing wall of theworking chamber in the geodetic lower area of the working chamber inwhich any existing sump liquid can collect without coming into contactwith the unattached blade ends of the impeller.

By this means, a complete partial switching-off of the liquid ringmachine. As a result, an adaptation of the suction capacity of theliquid ring machine to the required operating conditions is achievedthat is simple and effective. This ability to adapt to the actualoperating conditions is particularly advantageous, because the actualoperating conditions cannot be precisely ascertained in advance in aninstallation of this type. In this respect, it is possible for anoversized liquid ring machine to be installed. Operational costs canthen be considerably reduced by partially shutting down such a liquidring machine. Previously, such an adjustment had only been possible inan operation using several liquid ring machines. In contrast, the methodaccording to the present invention offers considerable savings ininvestment costs. Moreover, the space requirements for only one liquidring machine operated in accordance with the method of the presentinvention are also considerably less.

Regulating the internal pressure minimizes the energy consumed by thepart of the impeller operating at no load in a partial working chamberthat is switched off. In the case of such a pressure regulation, theaxial force being exerted on the impeller and, consequently, on theimpeller shaft due to the pressure differences existing between thepartial working chambers is kept negligibly small. It should also bementioned that the reciprocal actions are considerably reduced at thegap that is necessitated by the operation and exists between theimpeller of the liquid ring machine and the intermediate wallsurrounding the impeller.

Additional energy savings are achieved by keeping the sump liquidcollecting in the geodetic lower area of a switched-off partial workingchamber at a level where the sump liquid does not come in contact withthe impeller of the liquid ring machine.

The method can be advantageously implemented with a liquid ring machinewhich has, inside its machine housing, an impeller that is provided withblades. The impeller is rotationally mounted with its impeller shaft inside shields arranged on both sides of the machine housing so that theapex of the liquid ring machine lies in the geodetic upper area of theworking chamber. Partial working chambers are formed with at least onewall part provided on the impeller, which extends over the entireperiphery of the impeller from the impeller hub up to the unattachedends of the blades. There is on the machine housing at least oneintermediate wall that is radially aligned with the wall part of theimpeller. In addition, a discharge and suction connection is provided oneach side shield. The connections are each in interruptible fluid flowcommunication via a control element provided with a suction anddischarge slit with the respective partial working chamber. Also, eachpartial working chamber is able to be connected by itself with aliquid-discharge device and is provided with a separate operating liquidsupply.

The adjustment of the internal pressure of at least one switched-offpartial working chamber to more or less equal the internal pressure ofat least one partial working chamber remaining in operation succeedsquite simply in that at least on one side of the liquid ring machine,the mounted suction connection is in fluid flow communicationadditionally via an external conduit means with a partial workingchamber adjacent to the other side. The partial vacuum prevailing in theintake area that is in operation effects a draining of the switched-offpart of the working chamber without any additional auxiliary devices.

The internal pressure of a switched-off partial working chamber can beregulated in the desired manner because the external conduit means has apressure-reduction device.

For certain application cases, it can be advantageous to provide atleast one partial working chamber with a connection for a drainagedevice. For example, a compressed-air or vacuum ductwork system that isoften already available can be used to regulate the pressure economy ofa switched-off partial working chamber.

When the liquid ring machine has a bearing arrangement of the impellershaft that is able to absorb increased axial forces in addition toradial forces, it is also possible to implement the method according tothe invention without additional devices for regulating the pressureeconomy of a switched-off partial working chamber. The axial forcesoccurring in the case of unregulated internal pressure are then absorbedby the suitably designed bearing arrangement.

The impeller shaft may be supported in at least one side shield by adual-action tapered roller bearing. In addition to the radial forces,this bearing arrangement is able to absorb increased axial forces.

Although each partial working chamber by itself can be joined to aliquid-discharge device, the supply of operating liquid isadvantageously provided on at least one machine side with a shutoffelement so as to ensure right from the start that operating liquid willnot be unnecessarily supplied in the event of a partial cutoff. Theblocking of the supply of operating liquid can also take place as acontrolled operation.

The shaft seals, situated in the side shields, are constructed torestrict the entry of atmospheric gas into a switched-off partialworking chamber. Otherwise, the atmospheric gas pressure that ensues inthis passive part of the working chamber could adversely affect thepower efficiency of the liquid ring machine, or unnecessarily stress theautomatic control of the pressure economy for this partial workingchamber.

To be able to freely choose the partial working chamber to be switchedoff, it is advantageous to subdivide into equal-sized partial workingchambers so that the axial impeller subdivision and the intermediatewall are preferably arranged in the middle of the machine. Such asubdivision offers additional advantages from a standpoint of productionengineering, since both partial working chambers can be designed withequal dimensions.

To implement the method, it is advantageous to use a liquid ring machinewhose apex is situated in the geodetic upper area of the workingchamber. This ensures that the eccentricity of the impeller is selectedso as to provide adequate clearance between the unattached blade ends ofthe impeller and the inner housing wall of the working chamber in thegeodetic lower area of the working chamber in which any existing sumpliquid can collect without coming into contact with the unattached bladeends of the impeller.

The liquid ring machine can be partially drained quickly through aseparate drainage opening in each partial working chamber so that thepartial switching-off is able to be implemented immediately in case ofneed. The drainage opening of at least one partial working chamber maybe connected in each case to the operating liquid supply of at least oneother partial working chamber.

The operating liquid flowing out of the switched-off partial workingchamber in the event of a partial switch-off is fed to the supply ofoperating liquid of a partial working chamber currently in operation inthat the drainage opening of at least one partial working chamber isconnected in each case to the operating liquid supply of at least oneother partial working chamber.

Because the drainage opening of at least one partial working chamber isconnected to the compression area of at least one other partial workingchamber, the sump liquid collecting in the geodetic lower area of theswitched-off part of the working chamber is automatically suctioned intothe remaining working chamber currently in operation, since the pressureprevailing in the compression area of the partial working chambercurrently in operation is less than the pressure ensuing in aswitched-off partial working chamber, provided that no additional meansare provided for adjusting the internal pressure for the switched-offpartial working chamber. Consequently, no further precautions need to betaken for discharging the sump liquid.

One acceptable way to automatically recirculate the sump liquid in apartial working chamber that is in operation is connecting the drainageopening of at least one partial working chamber with the intake area ofat least one other partial working chamber. The pressure differencebetween the intake area of a partial working chamber that is currentlyin operation and a switched-off partial working chamber causes the sumpliquid to flow into a partial working chamber that is currently inoperation.

The above-mentioned connections that lead away from the outlet orificesof the partial working chambers are designed most effectively as pipes.These ducts can then be optionally arranged inside or outside of themachine housing.

It is possible to drain the partial working chamber provided for theswitch-off operation more rapidly and effectively, as well as toautomatically control the sump liquid overflowing into this partialworking chamber to a constant level by connecting at least onecontrollable extraction pump to the partial working chambers.

Due to the fact that the gap between the impeller and the intermediatewall surrounding the impeller is provided with a contact-free seal, thereciprocal actions at this gap, in particular the overflowing ofoperating liquid between a partial working chamber remaining inoperation and a switched-off partial working chamber are kept to aminimum. The inside radial edge of the intermediate wall has a fasteninggroove for a Teflon strip, whose width generally corresponds to thewidth of the gap between the impeller and the intermediate wall. Theintermediate wall may also have a continuous connecting port in thegeodetic lower area.

When no automatic control of the pressure economy is provided for aswitched-off partial working chamber, an internal pressure graduallyensues in this working chamber that is elevated compared to a pressureprevailing in the partial working chamber currently in operation. Thispressure difference can be utilized to discharge the sump liquid.Because an intermediate wall that divides up the partial workingchambers has a continuous connecting port in the geodetic lower area,the sump liquid flows back through this port, following the ensuingpressure drop into a partial working chamber that is currently inoperation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of an example of theliquid ring machine according to an embodiment of the present invention.

FIG. 2 is an exploded view of the liquid ring machine of FIG. 1

FIG. 3 is a detail view of area III in FIG. 1.

DETAILED DESCRIPTION

As shown in FIG. 1, the liquid ring machine 1 has a working chamberformed by a machine housing 3 that is closed off on the front side byflat control disks 2. Provided inside of this working chamber is animpeller 4 that is provided with blades and whose axis is arrangedeccentrically to the axis of the machine housing 3. The shaft 5 of theimpeller 4 is rotationally mounted in side shields 6 of the liquid ringmachine 1 connected to the machine housing 3. To seal off the shaft,stuffing-box packing (not visible) is provided in the side shields 6.

The impeller 4 is axially subdivided in the middle by a wall part 8,which extends over the entire periphery of the impeller 4 and reaches inthe radial direction from the impeller hub up to the unattached ends ofthe blades of the impeller 4. Lying in one plane with the wall part 8,an intermediate wall 9 is provided that concentrically surrounds theimpeller 4 and is fixed to the machine housing 3. A gap 14 necessitatedby the operation exists between the wall part 8 and the intermediatewall 9.

A subdivision of the working chamber into two equally sized partialworking chambers 10, 11 is given because of the wall part 8 and theintermediate wall 9, a distinction being made, furthermore, between aswitched-off partial working chamber; the passive partial workingchamber 11, and a partial working chamber currently in operation, theactive working chamber 10. Usually, both partial working chambers 10, 11have the same design and, consequently, each partial working chamber 10,11 is able to be used by itself as an active or passive partial workingchamber 10 or 11. In the drawing, only one partial working chamber isshown as a passive partial working chamber 11. This passive partialworking chamber 11 is provided with a drainage opening 12 which issuited for completely draining it and which is in fluid flowcommunication with a conduit means 19. A sump outlet 21 with a reliefconnection 13 is arranged in the geodetic lower area of the partialworking chamber 11.

Both partial working chambers 10, 11 are provided with discharge andsuction connections 20, only the suction connection 20 being visible inthe drawing. In FIG. 2, the suction and delivery slits 30 and 31 in eachcontrol disk 2 are shown. The flow paths flow medium flowing in throughthe suction connection 20 and flowing out through the dischargeconnection 26 are shown with arrows in FIG. 2. The passive partialworking chamber 11 is connected via a drainage line 22 with the suctionconnection 20 of the active partial working chamber 10. The drainageline 22 is provided with a control valve 23. A possible equally actingconnection of the active partial working chamber 10 with the suctionconnection 20 adjacent to the passive partial working chamber 11 is notdrawn in.

In the event of a partial switching-off of the liquid ring machine 1,the connection of the corresponding machine side 1 with the flow mediumvia the discharge and suction connections 20 is initially interrupted. Asuction pipe 27 is connected to the suction connection 20. The suctionpipe 27 can be blocked by a valve 28 to prevent flow medium from flowingso that the corresponding working chamber, for example partial workingchamber 11, is switched off. The separate supplying of the one partialworking chamber 11 with operating liquid is likewise switched off.Simultaneously with the blocking off of the supply of the flow medium,the supply of operating liquid is also blocked off for the partialworking chamber 11. This is done by a shutoff valve 25 arranged in theoperating liquid supply line 24. At the same time, the drainage opening12 is opened, so that the operating liquid of the now passive partialworking chamber 11 can flow out. In order to carry out drainage of theswitched-off partial working chamber 11 more quickly, a controllableextraction pump 29 can be connected to the drainage opening 12 to drainoperating liquid still present in the switched-off partial workingchamber 11. The operating liquid flowing out of the passive partialworking chamber 11 can be supplied via the conduit means 19 to theoperating liquid supply of the active partial working chamber 10.

After the passive partial working chamber 11 is emptied, the liquid ringmachine 1 works in a partially switched-off state. Operating liquid nowflows out of the active partial working chamber 10 through the gap 14necessitated by the operation between the wall part 8 and theintermediate wall 9, over to the passive partial working chamber 11. Asshown in FIG 3, a teflon strip 32 is inserted into a fastening groove inthe radial inside edge of intermediate wall 9 to seal the two partialworking chambers 10 and 11 relatively to each other. The teflon ring 32is a seal in the gap 14 between the wall part 8 of the impeller 4 andthe intermediate wall 9. As a result, a sump liquid 15, whose level 16,if at all possible, should not reach the blade area 17 of the impeller4, collects in the lower area of the passive partial working chamber 11.For this reason, to drain off the sump liquid 15 into both partialworking chambers 10 and 11, separate outlet orifices are provided, whichare only drawn in for the passive partial working chamber 11. In theexemplary embodiment depicted in the drawing, several possibilities fordeveloping the outlet orifices are shown, these outlet orifices beingable to be used individually or jointly. A sump drain 21 provided in thegeodetic lower area of the machine housing 3 serves as an outletorifice. The sump liquid 15 flowing out here can also be supplied viaanother relief connection 13 to the operating liquid of the activepartial working chamber 10. The sump drain 21 can also be connected to abarometric tube, whose level is determined by the internal pressure andthe level of the sump liquid. A connecting port 18 situated in theintermediate wall 9 likewise fulfills the function of an outlet orificefor the sump liquid 15. The sump liquid 15 flows through this connectingport 18 directly over into the active partial working chamber 10, sincein spite of an improved shaft seal as the result of properly designedstuffing-box packing, a pressure rise in the passive partial workingchamber 11 can take place and, as a result, a pressure drop from thepassive partial working chamber 11 toward the active partial workingchamber 10 ensues, which the sump liquid 15 follows.

In the case of an operation of the liquid ring machine 1 is necessary toregulate the internal pressure of the passive partial working chamber 11to be less than or, at the most, equal to the internal pressure of theactive partial working chamber 10. This is simply effected by connectingthe passive partial working chamber 11 via a drainage line 22 with thesuction connection 20 of the active partial working chamber 10. Thepartial vacuum prevailing at this point also ensues then in the passivepartial working chamber 11. Another possibility for intervention isgiven by a control valve 23 in the drainage line 22. Thus, the internalpressure of the passive partial working chamber 11 can be so adjustedthat, as already described, any existing sump liquid flows out throughthe outlet orifices provided for that purpose.

We claim:
 1. A method for operating a liquid ring machine comprising thesteps of:providing a working chamber within the liquid ring machine, theworking chamber having an apex in the geodetic upper area and arotatable impeller, wherein the working chamber is divided into at leasttwo partial working chambers; providing a supply of operating liquid;separating at least one partial working chamber from the supply ofoperating liquid; blocking the partial working chamber on either thesuction side or the discharge side or both; and draining the supply ofoperating liquid from the at least one partial working chamber so thatthe operating liquid does not contact the rotating impeller in the atleast one partial working chamber, while another partial working chamberremains in operation so that the operating liquid does contact therotating impeller in the another partial working chamber.
 2. The methodof operating a liquid ring machine according to claim 1, furthercomprising the step of:adjusting the internal pressure of a switched-offpartial working chamber to generally equal the intake pressure of atleast one partial working chamber remaining in operation.
 3. The methodof operating a liquid ring machine according to claim 1, furthercomprising the step of:maintaining a level of sump liquid collecting inthe geodetic lower area of a switched-off partial working chamber as aresult of operating liquid overflowing out of a currently operatingpartial working chamber at a level so that the sump liquid does notcontact the rotating impeller in a switched-off partial working chamber.4. The method of operating a liquid ring machine according to claim 2,further comprising the step of:maintaining a level of sump liquidcollecting in the geodetic lower area of the switched-off partialworking chamber as a result of operating liquid overflowing out of thecurrently operating partial working chamber at a level so that the sumpliquid does not contact the rotating impeller in the switched-offpartial working chamber.
 5. A liquid ring machine comprising:a housinghaving two opposite ends; a working chamber within the housing having ageodetic upper area and a geodetic lower area and an apex in thegeodetic upper area of the working chamber; two side shields, whereineach side shield is disposed at each of the housing ends; a shaftextending through the housing and rotatably mounted at opposite ends atthe two side shields; an impeller having a hub, wherein the impeller ismounted to the shaft; a plurality of blades attached at one end to theimpeller hub; at least one wall part on the impeller, wherein each saidwall part extends over the entire periphery of the impeller from theimpeller hub up to unattached ends of the blades; at least oneintermediate wall attached to the housing, wherein each saidintermediate wall is in radial alignment with the wall part of theimpeller and a gap exists between the wall part and the intermediatewall surrounding the wall part, and wherein the at least one wall partand the at least one intermediate wall cooperate to divide the workingchamber into at least two partial working chambers, each of the partialworking chambers being connectable to at least one liquid-dischargedevice; a plurality of operating liquid supplies for providing operatingliquid to the partial working chambers, wherein each partial workingchamber is connected to a separate operating liquid supply; twodischarge and suction connections, wherein each discharge and suctionconnection is connected to one of the side shields and has a controlelement with a suction and discharge slit so that each discharge andsuction connection is in interruptable fluid flow communication with oneof the partial working chambers; and wherein at least one partialworking chamber is separated from the supply of operating liquid and isdrained of the operating liquid at least to the point where the bladesof the impeller rotating in the at least one partial working chamber donot contact the operating liquid in the at least one partial workingchamber, and wherein the blades of the impeller rotating in anotherpartial working chamber do contact operating liquid in the anotherpartial working chamber.
 6. The liquid ring machine according to claim5, wherein sump liquid which collects in the geodetic lower area of aswitched-off partial working chamber as a result of operating liquidoverflowing out of a currently operating partial working chamber ismaintained at a level so that the sump liquid does not contact therotating impeller in the switched-off partial working chamber.
 7. Theliquid ring machine according to claim 5, further comprising an externaldrain line connected to at least one partial working chamber, whereinone of the discharge and suction connections disposed on one of the sideshields is also in fluid flow communication via the external drain linewith the partial working chamber adjacent to the other side shield sothat the internal pressure of a switched-off partial working chamber canbe adjusted to generally equal the intake pressure of at least onepartial working chamber remaining in operation.
 8. The liquid ringmachine according to claim 7, wherein the external drain line has apressure reduction valve.
 9. The liquid ring machine according to claim5, wherein at least one partial working chamber has a drainage deviceconnection.
 10. The liquid ring machine according to claim 7, wherein atleast one partial working chamber has a drainage device connection. 11.The liquid ring machine according to claim 5, wherein at least one ofthe operating liquid supplies includes a shutoff element.
 12. The liquidring machine according to claim 7, wherein at least one of the operatingliquid supplies includes a shutoff element.
 13. The liquid ring machineaccording to claim 5, further comprising two shaft seals, wherein eachshaft seal is disposed in one of the side shields to restrict the entryof atmospheric gas.
 14. The liquid ring machine according to claim 5,wherein the at least one wall part and the at least one intermediatewall are arranged in the middle of the liquid ring machine.
 15. Theliquid ring machine according to claim 5, wherein each partial workingchamber has a drainage opening suitable for completely draining thepartial working chamber.
 16. The liquid ring machine according to claim6, wherein each partial working chamber has a drainage opening suitablefor completely draining the partial working chamber.
 17. The liquid ringmachine according to claim 15, wherein the drainage opening of at leastone partial working chamber is connected to the operating liquid supplyof at least one other partial working chamber.
 18. The liquid ringmachine according to claim 15, wherein the drainage opening of at leastone partial working chamber is connected to a compression area of atleast one other partial working chamber.
 19. The liquid ring machineaccording to claim 16, wherein the drainage opening of at least onepartial working chamber is connected to a compression area of at leastone other partial working chamber.
 20. The liquid ring machine accordingto claim 15, wherein the drainage opening of at least one partialworking chamber is connected to an intake area of at least one otherpartial working chamber.
 21. The liquid ring machine according to claim16, wherein the drainage opening of at least one partial working chamberis connected to an intake area of at least one other partial workingchamber.
 22. The liquid ring machine according to claim 17, wherein thedrainage openings include pipes.
 23. The liquid ring machine accordingto claim 6, further comprising at least one controllable extractionpump, wherein one of the at least one liquid-discharge device isconnected to one of the at least one controllable extraction pump. 24.The liquid ring machine according to claim 7, further comprising atleast one controllable extraction pump, wherein one of the at least oneliquid-discharge device is connected to one of the at least onecontrollable extraction pump.
 25. The liquid ring machine according toclaim 5, wherein the radial inside edge of the intermediate wall has afastening groove to receive a Teflon strip, wherein the width of thegroove generally corresponds to the width of the gap between the wallpart of the impeller and the intermediate wall.
 26. The liquid ringmachine according to claim 5, wherein the intermediate wall has acontinuous connecting port in the geodetic lower area of the workingchamber.
 27. The liquid ring machine according to claim 6, wherein theintermediate wall has a continuous connecting port in the geodetic lowerarea of the working chamber.
 28. A liquid ring machine having a supplyof operating liquid, comprising:a working chamber having a lowergeodetic area and an apex in an upper area of said working chamber;dividing means for dividing the working chamber into at least twopartial working chambers; and an impeller rotatably mounted in theworking chamber, wherein the impeller is eccentrically located withinthe working chamber so that the rotating impeller adequately clears boththe inner wall of the working chamber and any operating liquid thatcollects in the lower geodetic portion of a switched-off partial workingchamber, wherein the switched-off partial working chamber is separatedfrom the supply of operating liquid and is drained of the operatingliquid at least to the point where the impeller in the switched-offpartial working chamber does not contact the operating liquid, andwherein the impeller rotating in another, not switched-off, partialworking chamber does contact operating liquid in the another partialworking chamber.
 29. The liquid ring machine according to 28, furthercomprising pressure adjusting means for adjusting the internal pressureof the switched-off partial working chamber to generally equal theintake pressure of at least one working chamber remaining in operation.30. The liquid ring machine according to claim 28, further comprisingsump level control means for controlling the level of operating liquidin the switched-off partial working chamber so that the operating liquiddoes not come in contact with the rotating impeller in the switched-offpartial working chamber.